This invention relates to four-way valves, especially of the type used in reverse cycle refrigeration systems. While the invention is described in particular detail with respect to such refrigeration systems, those skilled in the art will recognize the applicability of the invention to other uses and systems.
In refrigeration systems where the valve of this invention has utility, for example, it is common to connect a first condenser-evaporator coil, a second condenser-evaporator coil, and appropriate expansion devices to a single refrigerant compressor through the valve. The first coil ordinarily is an outdoor coil for condensing the compressor refrigerant, and the second coil is an inside coil for refrigerating the interior of an enclosure such as a room or other space. In heat pump applications, the function of the first and second coils can be reversed, making the indoor coil the condenser to heat the space and the outdoor coil the evaporator to absorb heat from the outside. Four-way valves permit easy change over between the functions of the first and second coils.
A number of four-way or piston slide valves are known in the art. In general, prior art valves have had rather complicated structure, often requiring tubing connections external of a main valve enclosure in order to accomplish valve operation. Often, the pilot valve assembly components are mounted externally of the main valve housing. Where the pilot valve assembly components have been positioned internally of the housing, their structure has increased the size of the housing, or imposed design limitations on the length of the main valve stroke. For example, conventional solenoids commonly are used for pilot valve activation. Designs for prior art valves have been relatively inflexible because the plunger of the solenoid requires some predetermined movement capability. The movement required for solenoid plunger operation, alone or in combination with known pilot valve assembly constructions, has limited the length of the main valve stroke.
The invention disclosed hereinafter eliminates these prior art difficulties by providing an improved, lowcost valve structure in which a pilot valve assembly is carried by and is movable with a main slide member. Means for operating the pilot valve assembly are operatively connected to that assembly, but the operating means and the pilot valve assembly are arranged so that the distance of the main valve movement may be increased or decreased appreciably, without affecting operating of the means utilized to actuate the pilot valve assembly. As indicated, the operating means commonly is a conventional solenoid. Because the valve design disclosed hereinafter incorporates a constant pilot stroke length, a single model solenoid may be utilized for a variety of pilot operated slide valves, individual ones of which have differing distance of travel for the main valve assembly.
One of the objects of this invention is to provide a four-way valve having simplified construction.
Another object of this invention is to provide a low-cost four-way valve.
Still another object of this invention is to provide a four-way valve having a main slide valve assembly, the stroke distance of which is independent of the stroke length of a solenoid device used to actuate the valve.
Yet another object of this invention is to provide a variety of four-way valve designs having different stroke lengths for the main slide valve assembly, but which employ a common solenoid actuating means.
Yet another object of this invention is to provide a pilot operated four-way control valve which is contained within the main valve enclosure but which does not limit movement of the main valve.
Still another object of this invention is to provide a four-way valve assembly which eliminates the necessity of any external tubular connections for proper valve operation.
Other objects of this invention will be apparent to those skilled in the art in light of the following description and accompanying drawing.